Rotary hook for sewing machines



Feb. 3, 1948. c. A. KEss'Lr-:R

I ROTARY HOOKS FOR SEWING MACHINES Filed sept. 24, 1946 Patented Feb. 3, L1948 1 2,435,358 ROTARY HGOK FOR SEWING MACHINES Charles A. Kessler,

Plainfield, N. J., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application September 24, 1946, Serial No. 699,019

4 Claims. 1

This invention relates to improvements in lockstitch sewing machines and more particularly to improvements in sewing machine loop-takers of the type known in the art as rotary hooks which are designed to cast loops of needle-thread about an interlocking bobbin-thread housed within a stationary thread-case forming a part of the looptaker, in the formation of lock stitches.

More specifically, the invention relates to improvements in a rotary loop-taker of the type disclosed in United States patents of Kessler No. 1,995,278, March 19, 1935, and No. 2,085,699, June 29, 1937.

When stitching fabrics containing a considerable amount of sizing, or other filler material, some of this material, under repeated thrusts of the needle, becomes dislodged and is deposited upon the hook. As the hooks were heretofore constructed, some of this material would find its way into the bearing between the relatively moving components of the hook and mix with the oil in said bearing, thus forming an effective lapping compound. In a comparatively short time, this compound grinds out the bearing, resulting in the failure of the loop-taker mechanism.

Therefore, it is the primary object of the invention so to construct the rotating portion of the hook and the stationary thread-case journaled therein that lint and other foreign matter will be excluded from the thread-case raceway in the hook to a degree not heretofore possible.

Another object of the invention is to provide an improved and enlarged bearing for the threadcase in a rotary hook, whereby the thread-case has a more nearly perfect support in the hook and therefore is less subject to tipping under the pull of the thread and, consequently, produces less friction, wear and noise. As is well understood, friction produces heat, especially in high speed machines such as lock stitch sewing machines in which it is not uncommon for the hook to rotate at speeds between 10,000 and 12,000 R. P. M.

In certain machines as heretofore constructed, and under certain working conditions, friction causes the parts to become heated to such a degree that the operator can change bobbins only with great difficulty and with a likelihood of having her fingers burned. Obviously, such friction and heat also cause wear in the parts and premature failure of the stitch-forming mechanism.

In view of the foregoing, it will be appreciated that any reduction in friction in a loop-taker, and the attendant reduction of heat therein, is highly important and particularly desirable, especially in 2 view of the fact that, when sewing at high speed, the operator is required, every few minutes, to remove the empty bobbin and replace it with a filled bobbin.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the drawings,

Fig. 1 is an outer or front face elevation of a rotary hook embodying the present invention, showing the beak of the hook as having taken a loop of needle thread from the needle; together with a portion of a work-supporting throat-plate, in section, and a portion of a rotation-restraining bar for the thread-case.

Fig. 2 is a front face elevation of the rotary hook and the thread-case carrier-member journaled therein, with the cap section of the threadcase removed.

Fig. 3 is a top view of the thread-case carriermember.

Fig. 4 is a, front face elevation of the rotary hook with the thread-case carrier-member therein, the latter being sectioned on the line 4-4 of Fig. 3, and with the thread-case retaining gib removed.

Fig. 5 is a front face elevation of the cupshaped hook-member with the usual segmental needle-loop-deecting and bobbin-thread pulloi plate secured thereto.

Fig. 6 is a detail sectional view taken on the line 6 6 of Fig. 4.

Fig. 7 is a perspective view of the hook member and segmental plate shown in Fig. 5 and showing the hook-member additionally fitted with an improved form of gib for holding the thread-case carrier-member in the hook-member. Y

Fig. 8 is a view similar to Fig. 7 with the improved gib removed.

Fig. 9 is a perspective view of the gib removed from the hook-member.

Referring more specifically to the drawings, the improved loop-taker is adapted to be embodied in lock-stitch sewing machines having a reciprocatory eye-pointed needle I, a work support including a throat plate 2, work-feeding mechanism, not shown, and a thread-case rotation-restraining bar 3 having a laterally projecting finger 4 loosely entering a notch 5 in a thread-case carrier member 6, later to be described. i

The loop-taker comprises a generally cupshaped hook-body member including a cylindrical side wall 1 and a bottom wall 8 which has a hub 9 adapted to be secured, by screws I0, upon a horizontally disposed rotary actuating shaft II, which, as is common in this type of sewing machine, makes two rotations for each reciprocation of the needle. The cylindrical side wall 'I of the loop-taker is partly cut away to provide, at its outer edge, a needle-thread-loop.seizing beak I2.. The beak I2 is opposed to, and'sligh'tly spaced from a loop-discharging tail or spur I3`pro`vided upon a segmental gib Ill detachably secured, as by screws I5, upony the cylindrical 'side wall l of the loop-taker. Y V l Detachably secured by screws I6 upon and Inserting the carrier-member into the. hook-body overlying a portion of the cylindrical side wa1l`1` of the loop-taker body `is a segmental sheet metal plate Il which serves as a needle-thread-loopldefleeting member and bobbin-thread pull-01T :device, as is well understood in the art.

The side wall of the loop-taker body 'I is cut away circumferentially to provide an internal raceway I8, comprising a cylindrical wall 18a, an outer wall |81 and an inner wall 42t; the outer side wall ib of said'raceway being, in paru-completed by a side ange I9 of the segmental and detachable gib I4. Journaled in the raceway .18., and thereby having a bearing 'support in the looptaker body, is .a Ybearing rib 20 Aformed uponand extending circumferentially of a generally cylindrical side wall 2l of the thread-case carriermember 6, hereinbefore mentioned. Thebearing rib 2t is interrupted to provide the usual'needlethread clearance gap g, a l-oop-detainin'g shoulder 22 'and a loop-confining shoulder 23. The length of the gap between the shoulders 22 'and 23 ismade as short as is permissible 'and yet afford ample clearance for entrance and exit of the loop of needle thread n thereby to `give a maximum circumferential length to the bearing rib 29. Disposed within the thread-case 'carrier-member '6 is a thread-case cap 4section Y211 containing a 'bobbin (not shown) of interlocking thread-if about which the needle-thread loops `are Ycast by the loop-taker in the formation of lock-stitches. The cap-section 24 is -releasably secured, by a ila-tch 25, to a central post rpor the carrier-member '6,

As hereinbefore stated, important features of this invention reside in "the Yspecific construction of the rotary hook member and the thread-ease .journaled therein, by means of which the threadcase is better supported in the hook 'and more accur-ately held against tipping therein as, Vi-or 'example, by the pull of the thread, and bymeans of which lint and 'other -foreign matter .is .more effectively excluded from the thread-case raceway I8. This has been accomplished by affording an improved Vbearing for the thread-'case and closing, to a greater extent than heretofore, the openings through which foreign matter may en-ter the raceway.

Obviously, the idealconstruction,would comprise a. completely annular and Vunbrokenrace- Way formed in the hook vbody and a completely annular 4bearing rib formed on the thread-case carrier-member and closely rviitted within vthe `racew-ay, Suchfa construction would aiordaioerfect bearing for the-thread-case and would exclude all lint Vand .dirt from .the raceway. Unfortu- 'matelyv vthat construction lis not possible, finas- 'much .as the needle-loop -must pass completely around the carrier-member. andthe .carrier-menif v,portion of the.racewaybehind the a portion of the bearing-rib, at the top edge of 'the 'carrier-member, is first placedv in the race- -waybehindthat Vportion of the outer wall which Eis integral with the hook-body.,l Next, the lower edge/ol vthe carrier member is swung inwardly to ,place the inner surface of the bearing rib into contact with the inner side wall 26 of the raceway;-and nally the removable gib is secured to the hook-body to hold Araceway.

With a .view to obtaining a maximum portion of the .raceway wholly within the hook-body and yet to permit removal andreplacement of the carrier-member E, I have machined a portion of the .raceway wholly within the hook-body `from a to b (Fig. 4) i. e. extending .backwardly from `the hook beak for approximately V degrees. Thisatfords an inwardly extending segmental flange?! which -merges -intQ the innerside wall vof the hook-body and constitutes a .portion of the -outerwal1:of the .raceway .48.; The remainder of the -raceway is open faced and adapted to be closed bythe side flange I9 of theremovable gib i4.V g

When the member 6 is in-the position shown in '.Fig. 4 relative to the hook body J i. e. with the shoulder 22 just short of contact with .the leading end of the ange 21, -the portion -of the ange 2l which overlies .the r'b v2li extending backwardly from thefshoulder 23 is'of .maximum permissible length. In .thisposition the clearancealforded by the gap g plus the slight amount'of clearance between `therib 2'9 andthe ange 2'1 is rjust sufficient to permitthe thread-case ,carrier-member to vbe placed intoand .removed from the A.hookbody. 'To aiord clearance and-thereby :facilitate the tipping movement-ofthe thread-case carriermember relative .tothe hook-body, when inserting the rib 2-0 .into Vand removing it from, that Ii-ange 2.1,',the rear edge of the upper portion of the rib .2-0 Ais chamfered, as at 28. F

The rear .wall vMi ofthe raeeway I8 extends,

unbroken, from thepoi-nt tot-he point yysee .Figs i45, 7 .and-8, and forms a `support `forzthfe Machinedrin 4the body` .portion ofthe Vvhook,:forwardly ofthe .wall 26 .and

rear .face of .the rib 20.

extending :from Athe :point 'c yto the .point d, Fig. 4 `is an arcuate recess *29 into which isLfitted-the outer edge Aportion 4'of the projecting iiinger Vof the'side iiange i9 forming apart of th-gib I4. vinasmuch as the finger 30 isziitted into the channel 29 the wall `3| thereof overlies Vand strengthens :the linger 30 land holds .it against deflection. `Fromy substantially'the point Z t'o the point e, theiiange I9 .is strengthened and .made rigid .by an integrally .formed skirt porti'on Ma extending ype-npendicular to the ifa'oe fof the `flan-ge. VThus, .in the present construction, the raceway :I8 is completely closed and .has rigid front 7andrearwalls fro" the point 'a to the -point eV or in other .wordsfor :an nnglepf .'315 vdegrees.

the carrier-member in the which lint and other foreign matter may enter the raceway.

From the foregoing it will be apparent that the present construction affords in the hook-body a closed raceway for the rib on the thread-case carrier-member which is of maximum length and the walls of which are sufficiently accurate and rigid to prevent any lateral tipping of said carrier-member by the pull of the thread, or otherwise. Likewise it will be apparent that the thread-case raceway is completely closed against the entrance of lint and other foreign matter except adjacent the needle-thread gap g between the shoulders 22 and 23 on the thread-case carrier-member.

Having thus set forth the nature of the invention, what I claim herein is:

l. A rotary hook for a sewing machine comprising a cup-shaped body member having a cylindrical side wall aording a loop-seizing beak and an internal thread-case raceway extending circumferentially approximately 315 degrees, said raceway having inner and outer side walls of which the entire inner side wall and that portion of the outer side wall extending rearwardly from the beak for approximately 80 degrees are provided wholly by the side wall of the body member; and a gib removably secured to said body portion and comprising the balance of the outer wall of said raceway, a portion of said gib being recessed into a portion of said body member, whereby said body member supports said gib against outward deilection, said body member and gib aording a continuous outer wall for said raceway throughout its entire length.

2. A rotary hook for a sewing machine comprising a cup-shaped body member having a cylindrical side wall affording a loop-seizing beak and an internal thread-case raceway extending circumerentially approximately 315 degrees, said raceway having inner and outer side walls of which the entire inner side wall and that portion of the outer side wall extending rearwardly from the beak for approximately 80 degrees are provided wholly by the side wall of the body member, said body member having formed therein, adjacent said raceway, an arcuate recess extending rearwardly approximately '70 degrees from that portion of the raceway formed wholly in said body member; and a gib removably secured to said body portion and comprising the balance of the outer wall of said raceway, said gib having an extended finger portion tted into the recess in said body member, whereby said body member overlies said iinger portion and supports it against outward deflection, said body member and gib affording a continuous outer wall for said raceway throughout its entire length.

3. A rotary hook for a sewing machine comprising a cup-shaped body member having a cylindrical side wall affording a loop-seizing beak and an internal circumferential thread-case raceway, said raceway having inner and outer side walls of which ther entire inner side wall and that portion of the outer side wall extending rearwardly from the beak for approximately degrees are provided wholly by the side wall of the body member, said body member having formed therein, adjacent said raceway, an arcuate recess extending rearwardly from that portion of the raceway formed wholly in said body member; and a gib having a skirt portion removably secured to said body portion and an integral finger portion iitted into said recess and projecting radially therefrom, whereby said body member supports said gib against outward deflection, said body member and gib affording a continuous outer wall for said raceway throughout its entire length.

4. A rotary hook for sewing machines having a cup-shaped body formed with a loop-seizing beak and a raceway, a thread-case having a circular bearing rib journaled in said raceway and having a gap in said bearing rib to provide a. loop-detaining shoulder and a loop-confining shoulder, said hook-body, in the region of said beak, having integral therewith an inwardly extending flange deflning the outer side wall of said raceway, said flange extending circularly approximately 80 degrees in a direction back from the -beak and merging into the inner side wall of said hook-body, said flange being of maximum allowable length in relation to the length of said gap as will permit assembly of the bobbin-case in the hook-raceway, and a gib detachably secured to said hook-body and having a portion merging into the trailing end of said flange thereby to provide a continuous outer wall for said raceway throughout its entire length.

CHARLES A. KESSLER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 480,181 Dial Aug. 2, 1892 2,242,955 Karle May 20, 1941 

